{"id":11506,"date":"2015-06-18T11:49:04","date_gmt":"2015-06-18T15:49:04","guid":{"rendered":"http:\/\/mjtsai.com\/blog\/?p=11506"},"modified":"2015-06-18T11:50:18","modified_gmt":"2015-06-18T15:50:18","slug":"core-data-bugs","status":"publish","type":"post","link":"https:\/\/mjtsai.com\/blog\/2015\/06\/18\/core-data-bugs\/","title":{"rendered":"Core Data Bugs"},"content":{"rendered":"

Almost four years ago, Dev<\/a> reported a bug with Core Data’s NSOrderedSet<\/code> generated accessors (via Ling Wang<\/a>).<\/p>\n

DaGaMs<\/a>, in 2013:<\/p>\n

I just brought this up with an Apple engineer during one of the CoreData Lab sessions at WWDC. They acknowledge the issue and that it’s a genuine bug, and from what I’ve seen it has the “critical” status, but of course there’s no promise as to when they’ll fix it. I don’t think it’ll be fixed in iOS6\/Mountain Lion. I think it’d be good to duplicate this radar further. Currently it has about 25 dup’s, the more the better!<\/p><\/blockquote>\n

It seems like an important and straightforward bug to fix, but it’s still present in iOS 9.<\/p>\n

Another bug, reported by Michael Gorbach<\/a> (tweet<\/a>):<\/p>\n

We have found a reproducible CD deadlock that can occur when using a fetched results controller with a “complex” (i.e. either multi-level or “synthesized” (not in the database) sectionNameKeyPath). This occurs specifically with a stack that has a top-level background (private queue) writing context, where the main thread context is a child of this context.<\/p>

Changes to CD (object creations and updates) as well as fetch requests, are taking place sequentially on background “import” contexts (private queue contexts). These contexts are also children of the top-level private queue writing context. If, while these CD changes and fetch requests are taking place in the background, the main thread Fetched Results Controller is asked to perform it’s initial fetch, a deadlock results.<\/p><\/blockquote>","protected":false},"excerpt":{"rendered":"

Almost four years ago, Dev reported a bug with Core Data’s NSOrderedSet generated accessors (via Ling Wang). DaGaMs, in 2013: I just brought this up with an Apple engineer during one of the CoreData Lab sessions at WWDC. They acknowledge the issue and that it’s a genuine bug, and from what I’ve seen it has […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"apple_news_api_created_at":"","apple_news_api_id":"","apple_news_api_modified_at":"","apple_news_api_revision":"","apple_news_api_share_url":"","apple_news_coverimage":0,"apple_news_coverimage_caption":"","apple_news_is_hidden":false,"apple_news_is_paid":false,"apple_news_is_preview":false,"apple_news_is_sponsored":false,"apple_news_maturity_rating":"","apple_news_metadata":"\"\"","apple_news_pullquote":"","apple_news_pullquote_position":"","apple_news_slug":"","apple_news_sections":"\"\"","apple_news_suppress_video_url":false,"apple_news_use_image_component":false,"footnotes":""},"categories":[4],"tags":[131,800,109,31,1017,904,1137,30,71],"class_list":["post-11506","post","type-post","status-publish","format-standard","hentry","category-programming-category","tag-bug","tag-concurrency","tag-coredata","tag-ios","tag-ios-5","tag-ios-8","tag-ios-9","tag-mac","tag-programming"],"apple_news_notices":[],"_links":{"self":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/11506","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/comments?post=11506"}],"version-history":[{"count":2,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/11506\/revisions"}],"predecessor-version":[{"id":11508,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/11506\/revisions\/11508"}],"wp:attachment":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/media?parent=11506"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/categories?post=11506"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/tags?post=11506"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}